Sign support material

ABSTRACT

A SIGN SUPPORT MATERIAL COMPRISING AN UPPER FACE OF PHENOLIC RESIN IMPREGNATED PAPER, A LOWER FACE OF PHENOLIC RESIN IMPREGNATED PAPER, AND A WIRE SCREEN INTERPOSED BETWEEN THE TWO FACES. THE TWO FACES ARE BONDED ONE TO THE OTHER THROUGH THE WIRE SCREEN THEREBETWEEN. THE MATERIAL IS A RIGID, COMPACT, REINFORCED LAMINATE PARTICULARLY ADAPTED FOR USE IN EXTERIOR OR OUTDOOR APPLICATIONS AS HIGHWAY SIGNS, COMMERCIAL SIGNS, AND INDUSTRIAL SIGNS.   D R A W I N G

y 11, 1972 R. P. LOGAN 167 6281 4 SIGN SUPPORT MATERIAL Filed July 29, 1970 I NVENTOR.

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v United States Patent Oflice 3,676,281 Patented July 11, 1972 3,676,281 SIGN SUPPORT MATERIAL Robert P. Logan, Tustin, Calif., assignor to Eagle-Picher Industries, Inc., Cincinnati, Ohio Filed July 29, 1970, Ser. No. 59,104 Int. Cl. B32b 15/14, 29/02 US. Cl. 161-85 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to laminates and, more particularly, relates to a laminate especially adapted for use as a sign support material.

One of the major uses for sign support materials is for street, road and highway signs. A particularly large use is for signs for interstate highways that have been built throughout the last decade. These automobile thoroughfaries require an enormous annual amount of sign materia Signs which are used on streets, roads and highways, as well as many commercial and industrial signs are located out of doors, and are continuously subjected to weather. The support material of such outdoor signs must be able to withstand the effects of rain, snow, sleet, hail, and high winds. Further, the surface of such sign support material must be such that same can be painted or otherwise conditioned with the requisite directions or indicia, i.e., provided with a sign face, appropriate to the use desired.

By reason of those requirements, by far the majority of signs adapted for use in an outdoor or exterior environment use sheet metal as the sign support material when the sign is simply flat or plate-like in geometry. Sheet metal can be readily painted with weatherproof paint that withstands the outdoor weather. Further, the metal itself is relatively unaffected by the weather. Sheet metal provides a safety factor in the sense that it does not shatter or break into high velocity pieces when struck by a vehicle. Practically all street, road, and highway signs today use sheet metal, e.g., aluminum, as the sign support material.

It has been one objective of this invention to provide a novel sign support material, and method of making same, that is particularly adapted for outdoor use such that it will not harmfully degrade upon being exposed to the weather for a lengthy period of time.

It has been another objective of this invention to provide a novel sign support material, and method of making same, which is comprised of a resin impregnated sheet laminate that minimizes fragmentation into high velocity pieces if subjected to a force sufficient to break the laminate.

It has been a further objective of this invention to provide a novel sign support material, and method of making same, that results in a resin impregnated sheet laminate adapted to be readily provided with a sign face that is inexpensive to manufacture relative to the cost of the ordinary sheet metal signs such as are in common use today for traffic signs and the like.

The novel sign support material of this invention comprises an upper face of phenolic resin impregnated paper, a lower face of phenolic resin impregnated paper, and a wire screen interposed between the two faces. The two faces are bonded one to the other through the wire screen held therebetween. Such material has been found to be rigid, compact, and particularly adapted for use in exterior or outdoor applications as highway signs, or commercial signs, or industrial signs. This sign support material does not fragmentize into high velocity pieces upon being subjected to a breaking force, is not adversely affected upon prolonged exposure to the weather, can be readily painted as desired, and permits the manufacture of sign blanks at a cost substantially less than the cost of sheet metal sign blanks.

The breakage characteristics of a laminate formed in accordance with this invention are to be contrasted with those of a laminate which does not include the wire mesh. When a laminate without wire mesh is stressed to the breaking point, it shatters explosively and fragments are projected like shrapnel at very high velocities. The violence and speed of expulsion of the fragments is so great that serious damage or injury can be caused. In comparison, the laminate of this invention requires a substantially higher loading to break it, and when it does break the resulting pieces are separated but are not projected at high velocity; in this respect it is believed that the wire mesh is placed in shear and deforms relatively gradually in comparison to the yield rate of the paper. In the process the wire strands absorb energy that would otherwise be released as kinetic energy in velocity of pieces. Unlike safety glass, the wire does not hold the pieces together to prevent their scatter, but rather minimizes the velocity at which pieces travel from the point of breakage.

For the purposes of this application, the phrase sign support material is deemed to mean the backing or rigid support for the sign face; the phrase sign blan is deemed to mean a piece of sign support material that is cut to size with edges, corners and holes as required; the phrase sign face is deemed to mean the coating with lettered or other indicia, whether by painting or otherwise, which provides the message delivered by the sign; and the word sign is deemed to mean the composite of a sign blank and a sign face.

Other objectives and advantages will be more apparent from the following detailed description taken in conjunction with the drawings in which:

FIG. 1 is a cross-sectional view illustrating the final laminated, sign support material of this invention; and

FIG. 2 is a diagrammatic view illustrating the method of making the sign support material of this invention.

As illustrated in FIG. 1, the sign support material 10 of this invention is comprised of an upper face 11 of phenolic resin impregnated paper, a lower face 12 of phenolic resin impregnated paper, and an intermediate 13 of a metal wire screen. The screen 13 is preferably of a metal such as aluminum, copper or steel. Generally speaking, it has been found that fiber glass or synthetic fiber screens are not desirable because of their tendency to absorb the phenolic resin and/ or become brittle after lamination. The character of the screen is preferably such that it possesses a mesh size between about 12 wires/inch x 12 wires/inch and about 24 wires/inch x 24 wires/inch; and the gauge of the wire is preferably between about 5 mils and about 25 mils. The lighter wire gauges are used with the smaller screen mesh sizes and the heavier wire gauges are used with the larger screen mesh sizes. A gauge size above the maximum stated and a mesh size below the minimum stated results in poor adhesive or laminate characteristics of the upper 11 and lower 12 faces one to the other through the screen 13. Such lamination or adhesion of the faces 11, 12 one to the other through the screen 13 is most important to insure oneness of the laminate, i.e., to prevent delamination of the various laminae one with the other, when the sign support material is in use. On the other hand, a mesh size greater than the maximum which is preferred and a gauge size less than the minimum preferred often results in a sign support material which tends to fragment into high velocity pieces almost as though no screen were used upon being subjected to a heavy blow of force such as may occur when the sign is struck by an automobile, and which tends to have an undulated or ribbed or irregular surface which is not usually desirable in a sign. One of the paramount advantages of the sign support material 10 of this invention is that the laminate will not fragment into high velocity pieces, and it is toward this end that the wire screen 13 is an important functional element. Without a wire screen 13 interposed between the upper 11 and lower 12 faces of phenolic resin impregnated paper, the sign support material 10 would readily fragment into high velocity pieces, upon being subjected to a blow sufiicient to break same, and angulated, randomly shaped pieces having quite sharp edges and points would be scattered forcefully around the area in which the sign was located. Thus, the wire screen 13 surprisingly substantially eliminates fragmentation of the sign support material into high velocity pieces upon same being subjected to a breaking force.

The upper 11 and lower 12 faces of the sign support material 10 are composed of a series of phenolic resin impregnated paper sheets 14, Le, core stock sheets. The number of core stock sheets 14 used to make up each face 11, 12 of the sign support material 10 is primarily dependent on the thickness desired of the final sign blank. Preferably a kraft-type paper is used, and preferably the paper has a basis weight, i.e., a weight per 3000 square ft., of between about 45 lbs. and about 160 lbs. A paper basis weight of below about 45 lbs. has been found economically inefficient in that more phenolic resin is required, and at the same paper impregnating line speeds a lesser weight of impregnated paper results. A paper basis weight of greater than about 160 lbs. has been found to present practical problems in achieving adequate impregnation of the paper sheet at production line speeds.

The phenolic resin used for impregnating the paper may be either a so-called A stage or resole resin, or a so-called Novolac resin. The A stage resin is created by the reaction of phenol and aqueous formaldehyde in the presence of an alkali to form a methylol phenol. The Novolac resin is formed by reacting phenol and aqueous formaldehyde in the presence of acid and less than 0.86 mol of formaldehyde per mol of phenol to yield a diphenolmethane polymer. The A stage or Novolac resin is then solubilized in a carrier liquid, for example, methanol, to form a phenolic resin varnish.

This phenolic resin varnish is coated onto the sheets of paper. By additional heating of the A stage resin, or by the addition of more formaldehyde to the Novolac resin, during the coating process further polymer condensation takes place with the formation of a B stage product that is a fusible resin. Preferably the phenolic resin is coated onto and impregnated into the paper in an amount between about by weight and about 40% by weight of the total coated sheet weight prior to lamination. It has been found that a coating of less than about 20% by weight results in poor lamination and adhesion of the sheets 14 one to the other, poor weatherability characteristics for outside use, and poor impact resistance because of the low bond strength. A coating of greater than about 40% by weight results also in poorer impact resistance because the final C stage resin is brittle.

The coating of the paper with the phenolic resin varnish can be accomplished with method and apparatus shown in FIG. 2. First, a continuous web 16 of kraft paper from a supply roll 17 is passed through a pair of tensioniug rolls 18 into a bath 19 of the varnish. Preferably the bath is an A stage resin in a methanol solution. The web 16 is passed beneath immersion rolls 21 located in the bath 19 and directed out of the bath through a pair of squeeze rolls 22. The degree of saturation, and weight of phenolic resin applied to the web 16, is governed by adjusting the gap or nip between squeeze rolls 22. Doctor blades may be used in place of the rolls 22 to control the weight of resin applied. From the squeeze'rolls 22 the web 16 is passed through oven 23 where it is dried and where the A stage resin is converted to the B stage product. The now phenolic resin impregnated web 16 is cut by knife 24 to length into a series of core stock sheets 14 which are stacked as at 25, prior to laminating same together with the wire screen 13 into the sign support material 10.

Once the paper web 16 has been impregnated with the desired weight of the phenolic resin, and once the impregnated sheets 14 and wire screen 13 have been cut to the desired size, same are assembled in overlying or stacked or sandwiched relation, as at 26. As many sheets 14 of the phenolic resin impregnated paper may be used to form the upper 11 and lower 12 faces of the sign support material 10 as are needed to achieve the final thickness desired for the sign support material. After the phenolic resin impregnated sheets 14 which comprise the upper 11 and lower 12 faces, and the wire screen 13, have been layed up in proper relation the resulting stack is subjected to a pressure-heat cycle by platens 27. This pressure-heat cycle causes the B stage resin impregnated in the paper to cure in the mold and to yield a highly cross-linked, insoluble and infusable C stage prdouct. Further, by means of the pressure-heat cycle the various lamina or sheets 14 of the upper 11 and lower 12 faces are adhered one to the other, and the upper and lower faces are strongly adhered one to the other through the interstices or mesh openings of the wire screen 13, thereby forming the desired sign support material of this invention.

The cost of the sign support material 10 formed in accordance with this invention is substantially less than sheet metal normally used for exterior signs, and particularly used for highway signs as explained above. Further, even though the individual upper 11 and lower 12 faces of the sign support material 10 of this invention by'themselves would readily fragmentize into high velocity pieces upon being subjected to a force sufficient to break same, because the wire screen 13 is incorporated into the center of the laminate, and because the two faces are laminated one to the other through that screen, the resultant sign support material has an acceptable impact strength and does not fragmentize into high velocity pieces upon breakage. Further, the exposed surfaces of the sign support material 10 are smooth and readily accept paint. Further, the sign support material does not harmfully degrade upon prolonged exposure to the weather.

The following example illustrates one preferred embodiment of my invention.

EXAMPLE Untreated kraft paper of pounds basis weight is passed through a bath of phenol-formaldehyde, A stage resin varnish as shown in FIG. 2, and then dried in an oven where the A stage resin is converted to a B stage product. The dry Weight of the phenol-formaldehyde resin picked up or coated on the kraft paper is 24% by weight of the total impregnated paper or core stock weight. The phenolformaldehyde used is sold under designation No. RF9254 by Monsanto Company, St. Louis, Mo.

Six core stock sheets of the resin impregnated kraft paper are cut to the same size for each of the upper and lower faces of the resultant sign support material. An aluminum wire screen having a mesh of 18 wires/inch x 16 wires/inch, the wire having a gauge of 11 mils, is cut to that same size. The core stock sheets and screen are then layed up one on top the other with the screen being placed between the sixth and seventh sheets of the stack. Subsequently the stack is subjected to a pressure of about 1100 p.s.i. at a temperature of about 260 F. to about 290 F. for approximately 20 minutes.

The resultant laminate of sign support material has all the characteristics preferred in the sign support material of this invention and is about .08 inch in thickness. The sign support material formed in the manner described is cut into sign blanks. The sign blanks are subjected to a paint adherence test, to a weatherometer test, and to a water immersion test; in each instance the results of the test are satisfactory.

In the paint adherence test, two sign blanks are painted with yellow, oil base paint, one sign blank being painted on one side only and the other being painted on both sides. Both blanks are lightly sanded prior to painting. Each painted side of the sign blanks is then scribed into A; inch squares with a razor blade. Thereafter, the blanks are then each immersed in 100 F. distilled water for 100 hours. After immersion, a strip of adhesive tape is firmly pressed against the painted surface of the sign blanks and then removed; no lifting of a painted square is noted.

In the weatherometer test, two sign blanks are painted with yellow, oil base paint, one being painted on one side only and the other being painted on both sides. The blanks are then subjected to ultraviolet light. This exposure is interrupted every 3.8 hours with one hour of water spray until a total of 100 hours ultraviolet light exposure is achieved. Neither of the samples show any detectable change in color or texture.

In the immersion test, a sign blank with unprotected edges and unprotected, unpainted surfaces is placed in a bath of water at room temperature for 30 days. No warpage or splitting of the laminae is visibly observed.

Having described the preferred embodiment of my invention, what I desire to claim and protect by Letters Patent is:

1. A sign support material particularly adapted for use in the fabrication of sign blanks for outdoor use, said material being substantially impervious to weather, comprismg an upper face made up of a series of paper sheets impregnated with a phenolic resin,

a lower face made up of a series of paper sheets impregnated with a phenolic resin,

said paper being a kraft-type paper having a basis weight between about 45 lbs. and 160 lbs., and said resin being present in said paper sheets in an amount between about 20% by weight and 40% by weight of the total core stock sheet weight, and

a wire screen interposed between said two faces, the

sheets of said two faces and the sheets on each side of said wire screen being intimately bonded throughout one to the other by the application of heat and pressure to a stack of said sheets and wire screen, said wire screen having a mesh size between about 12 wires per inch x 12 wires per inch and about 24 wires per inch x 24 wires per inch and the gauge of the wire being between about 5 mils and 25 mils. 2. A sign support material as set forth in claim 1 wherein said phenolic resin is a phenol-formaldehyde resole.

3. A sign blank particularly adapted for outdoor use, said blank being substantially impervious to weather, comprising an upper face made up of a series of paper sheets impregnated with a phenolic resin, a lower face made up of a series of paper sheets impregnated with a phenolic resin, said paper being a kraft-type paper having a basis weight between about 45 lbs. and lbs., and said resin being present in said paper sheets in an amount between about 20% by weight and 40% by weight of the total core stock sheet weight, and a wire screen interposed between said two faces, the sheets of said two faces and the sheets on each side of said wire screen being intimately bonded throughout one to the other by the application of heat and pressure to a stack of said sheets and wire screen, said wire screen having a mesh size between about 12 wires per inch x 12 wires per inch and about 24 wires per inch x 24 wires per inch and the gauge of the wire being between about 5 mils and 25 mils.

References Cited UNITED STATES PATENTS 1,362,887 12/1920 Moist 16185 3,084,085 4/ 1963 Ronay 161-85 396,704 1/ 1889 MacDonald 40135 1,201,756 10/1916 Perry 1611l5 1,573,898 2/ 1926 Armstrong 40-135 2,489,541 11/1949 Read 161-115 2,801,198 7/1957 Morris et al. 161-263 X OTHER REFERENCES Hackhs Chemical Dictionary 4th edition, Julius Grant (ed.) McGraw-Hill (1969), p. 579 relied on.

ROBERT F. BURNETT, Primary Examiner R. O. LINKER, JR., Assistant Examiner 

